The statements above, if true, best support which of the following assertions about commuting in the congested urban areas mentioned above?

(A) Waiting in traffic accounts for approximately 25 percent of the commuting time for individuals who drive to their destinations.---Irrelevant

(B) Walking between a subway or train station and one's final destination does not, on average, take longer than walking between one's car and one's final destination.--Irrelevant

(C) Using carpool lanes does not, on average, reduce driving time by more than 25 percent.--Correct- Because the argument does says that commuting through public modes decreases travel time by 25% while travelling through carpool lane might decrease the travel time but not up to 25%. Leading to the total commuting time to be more than the commuting time required to travel via public modes

(D) Individuals who commute via public buses spend approximately 25 percent more time in transit than those who commute using public trains or subways--Public buses not mentioned--Irrelevant

(E) Subways and trains are available in the majority of congested urban areas.---Nothing is mentioned about availability if subways or trains- Irrelevant

IMO C

Hope this helps